A FePt alloy can be provided with the fct (Ordered Face Centered Tetragonal) structure which has high crystal magnetic anisotropy by heat-treating at an elevated temperature (for example, at 600° C. or higher), and therefore a FePt alloy has been highlighted as a magnetic recording medium. To make FePt particles smaller and more uniform in the thin film of the FePt alloy, it is proposed that a predetermined quantity of carbon (C) be included into the thin film of the FePt alloy (for example, Patent Literature 1).
However, the formation method of the FePtC thin film, described in the Patent Literature 1, is the method of vapor-depositing Fe, Pt, and C simultaneously on a MgO (100) board by using the Fe target of a 2-inch diameter, C target of a 2-inch diameter, and the Pt target of 5 mm in height and width. In this method, it is difficult to obtain the film whose composition is controlled strictly. Additionally, three targets are required and each target needs a cathode, a power supply, etc, and so the cost of equipment becomes high while the preparatory work of sputtering takes time and effort.
On the other hand, the technology for producing the sputtering target consisting of a PtFe system alloy according to a casting process is described in the Patent Literature 2. And in claim 2, 3 and the paragraph 0017 of a Patent Literature 2, C is raised as one choice in the many choice of the element added into a PtFe-based alloy.
However, C is only raised as one of the many choices of the element added into a PtFe-based alloy, and the specific working example in which C is actually added into the PtFe-based alloy is not shown. Even if C can be added into a PtFe-based alloy in the technology described in the Patent Literature 2, the content of carbon (C) in a FePt—C sputtering target is 20 at % at the maximum as described in claim 2, 3 and the paragraph 0017 of a Patent Literature 2.